A hair styling device of this type is discussed, for example, in EP 1 030 571 B1. The metallic molded parts of this hair styling device are covered with a thin layer of lacquer or anodized, if the molded parts are made of aluminum or an aluminum alloy, treated by means of an anodizing method (in order to produce an oxide layer). These lacquer layers or oxide layers are respectively applied onto the molded parts in order to realize a smoother surface than that of non-treated metallic molded parts such that the hairs to be styled are subjected to the least mechanical stress possible when the hair styling device is used. The hairs are subjected to this stress due to the fact that the hair strands to be styled are clamped between the molded parts during the styling process and a clamping force acts upon these hair strands. The hair styling device is moved along the hair strands with a tensile force while the hairs are heated by the heating part. The effectiveness of the hair styling process increases proportionally with the intensity of the tensile force exerted upon the hairs. However, the intensity of the tensile force has an upper limit. This limit is defined by damage to the hairs that is caused by the mechanical stress resulting from the tensile force and the simultaneous thermal stress. If the tensile force is excessive, the user also experiences unpleasant tension at the hair line that is caused by the movement of the hair styling device relative to the hair.
In known hair styling devices in which the molded parts of aluminum or an aluminum alloy are provided with anodized contact surfaces, the average surface roughness amounts to approximately 4 μm. However, this surface roughness does not rule out damage to the hairs and unpleasant tension at the hair line because the hair surface itself has a structure between 3 μm in 7.5 μm and the hairs therefore have inferior sliding properties between the contact surfaces of the molded parts. The unpleasant tension at the hair line also makes the hairs more susceptible to damage because the potential dwell time of the hairs between the contact surfaces is longer in this case. It has been determined that galvanized contact surfaces typically result in the hairs sliding excessively fast between the contact surfaces such that no satisfactory styling of the hairs can be achieved.
What is needed, therefore, is a hair styling device that avoids unacceptably high damage to the hairs and stress on the hairs, as well as unpleasant tension at the hair line of the user. The heating of the hairs for the styling process should also be optimized.